It is common practice in the automotive industry to assemble the door components of a motor vehicle in an assembly line operation, which can often cause problems due to the relative complexity of the door assembly and its various components. For example, in assembling the door, the door is typically made up of two basic metal structural panels, to which is ultimately attached an interior, finished, trim panel, within which layered panel structure a number of mechanical and electrical components must be assembled. These include the window lift mechanism, the door latch and lock mechanism, the various electronic components, wiring and switches, etc., especially where the mechanical components are to be powered components, and also possibly including a door mirror assembly with its mechanical and electrical interfacing components.
Making this relatively complex assembly as the motor vehicle moves down the assembly line causes time and procedural problems with respect to the assembling and finishing of the rest of the motor vehicle.
Some attempts have been made in the past to try to alleviate this assembly line problem. For example, a door unit for motor vehicles has been disclosed in U.S. Pat. No. 4,648,208 (issued March 10, 1987 to Baldamus et al). The unit includes a unit carrier which has a number of the door's mechanical components mounted within it, which unit carrier can be attached to the interior trim panel in a preassembly operation. In particular, the complete window lift assembly (with or without the window) can be included in the unit carrier, along with possibly others of the door's mechanical components.
However, the Baldamus approach requires the inclusion of tubular reinforcing members, typically two vertically spaced ones running the width of the door, or a reinforced plate or other form of structural reinforcement. Thus, the Baldamus "trim panel" is actually turned into a structural support and reinforcement panel, changing the function of the panel from primarily a decorative trim panel with relatively no structural import to one of primary structural import.
The present invention considers it more desirable preferably to retain the initial assembling of all of the primary structural support or framing members on the main assembly line in the assembly plant, and preassembling the trim panel with its selected modular units, i.e. selected mechanical and electrical components, resulting in a trim panel which has relatively little structural, reinforcement capabilities, retaining its primary panel function as one of aesthetic trim and not of structural import.
The remainder of the door, particularly the door frame and the crash bar(s), typically made of metal or other structural strong material, is assembled on line at the assembly plant. These parts are designed to be able to take, for example, thousands of pounds of crash loads.
Another problem which exists in the prior art, including the Baldamus device, is the need for structural support and positioning of the various components, which are to be mounted on the trim panel, whether it also is converted into a structural strengthening reinforcement member, like in Baldamus, or not. One patent (U.S. Pat. No. 4,471,251 issued Sept. 11, 1984 to Yamashita) went to the extreme of suggesting that a motor mount structure for, for example, the window lift drive motor, would include a pair of casing halves, one of the casing halves being an integral part of two separate panels for the automotive door structure, including the basic door frame member. However, this creates serious problems of alignment and interfacing, among other things.
Other serious problems also exist in the prior art with respect to on-line assembly of vehicle doors and in providing modular door assemblies.